Carburetor



Sept. 4, 1934. H, w LINKERT CARBURETOR A Filed April 2, 1930 4 Sheets-Sheet l SePt- 4, 1934- H. w. LINKERT 1,972,743

l CARBURETOR Filed April 2, 1930 4 Sheets-Sheet 2 Sept 4, 1934- H. w. LINKERT 1,972,743

CARBURETOR Filed April 2, 1930 4 Sheets-Sheet 5 m \1 N Q l\3 N LQ u N y EN i3 k1 Am @H a v N) f Sept. 4, 1934. H, w. LINKERT CARBURETOR Filed Aprii 2, 1930 4 Sheets-Sheet 4 Patented sept. 4, 1934 1,972,743v

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Howard W. Linkert, indianapolis, llnd., assigner, by mesne assignments, to Marvel Carburetor Company, Flint, Mich., a corporation of noia Application Apn'i 2, 193e, semi No. tiesto is claims. (ci. 2er- 34) This invention relates to Vcarburetors for ininvention will be apparent from the disclosures ternal combustion engines and has special refin the specification and the accompanying erence to an improved type of plain tube carbudrawings. retor. This invention (in a preferred form) is illus- 5 It is an object of this invention to provide an trated in the drawings and hereinafter more improved carburetor of the class described fully described. which will supply an emcient and economical On the drawings: carburetted fuel and air mixture at various Figure 1 is a plan view of a carburetor emspeeds and loads together with a richer mixbodying the features of this invention.

l ture at maximum demand. Accordingly, my Figure 2 is an elevational view from the air 65 invention provides a plain tube carburetor havinlet side thereof'. ing an idling fuelfeed increasing in quantity Figure 3 is a central vertical section on the as the throttle is opened and merging smoothly line III- III Lof Figure l. into the mixture supplied by the normal fuel Figure 4 is a partial section on the line IV-IV l5 feeding system, which upon first coming into of Figure 2 showing the accelerating pump in 70 action is temporarily enriched by the emptying section with other parts in elevation. of a fuel well which thereupon becomes an air Figure 5 is a section on the line V-V of bleed connection to economize fuel under steady Figure 3 showing the idling bypass and maxoperation at .part throttle. Sincethe metering imum-minimum fuel valve.

characteristics of an air bleed nozzle do not Figure 6 is a partly diagrammatic showing vof 75 increase in step with an increased air flow as the carburetor, with the various fuel control the throttle is further opened the normal acceldevices transposed into a single plane.- erating pump fuel supply is so arranged as to As shown on the drawings: feed into the main nozzle at higher suctions The illustrated carburetor ,is of the plain'tube aside from its functions in providing a tempotype in which a single fixed venturi is used. '80 rarily enrichened mixture for accelerating pur- Normally all the air except that which passes poses. through this fixed system passes through this It is another object of this invention to proxed venturi. All the metered fuel, except the vide an improved accelerating pump structure idle fuel and starting and warming upA fuel,

adapted to provide a delayed and prolonged fuel passes through a nozzle-whose tip extends into 85 injection relative to the actuating movement of the throat of vthe venturi and the fuel mixes at the pump linkage connected to the throttle. To the throat of the venturi with the air-.passing this end, I provide a retarded lost motion conthrough. There are vno moving parts controlnection between the pump and throttle to perling the normal metering of the fuel except mit minor movements of the throttle without a maximum flow valve *which is opened-bythe ,99.

actuation of the pump, and I prolong the period throttle when the latteiisi-opened?,'wide -and f f 1at the expense of i of y pump discharge by providing a Weighted folmaximum power is desire n metering: charm",- if

lower above the piston which follower forces:V the more economical normal] additional fuel into the main nozzle after theV teristics;v

40 piston stops moving 'to give the desirable follow The caburetor body (ioIIjfpr-isfs im- 951i I up required for proper acceleration. The deber incorporating anoutlct mixtfurepasage j layed flow, total amount and rate of initial and 10, containing?` amthrttl `valvej"11f1n'`" ashaft i l delayed flow can be regulated by properly pro- 12, and a cover 13 for a", oatbowl 14-ln 'a lower portioning theY piston size, follower weight and member 15 containing an air inlet passage 16.k

piston and outlet orifices. The `fixed venturi 1'7 is interposed between the 100 It is another object of this invention to promixture outlet passage 10, and' the air inlet vide an improved and simplified plain tube car-l passage 16. FueL enters the4 float bowl 14 buretor with the minimum of moving or adjustthrough an inlet 18 formed on the cover 13, the able mechanismsthat will still vary the effecadmission of the fuel being regulated by a. float tive nozzle passage and discharge for economical 19.

and maximum power conditions and wherein the The main fuel nozzle 20 is fed in three ways effective nozzle passage varies according to the from the float bowl. First, the normal requiresuction due to a supplementary fuel flow at high ments flow from the bowl through inlet ports suctions. into a metering pin housing 21 containing au, Y Other and further important objects of this double diameter metering pin 22, which in its 110 creasing the effective area of the orifice to in-` crease the flow of fuel.

Av throttle operated accelerating pump is provided, the cylinder 28 of which, is fed fuel from the float chamber through a passage 29 and non-return valve 30. From the pump cylinder a discharge passage 31 leads into a plug 32 inserted in the lower end of the nozzle charn-` ber 25 and containing a ball check valve 33. This plug carries a restricted or accelerating discharge nozzle 34 extending upwardly within. the main nozzle passage 35. Besides furnishing extra fuel when the throttle is being opened,'

the accelerating system above described supplements the regular fuel supply passing through the main nozzle under high suction conditions. When the throttle is held nearly constant fuel enters the pump cylinder through the nonreturn valve an'd thence into the nozzle through the accelerating nozzle 34.

The third source of fuel supply to the main nozzle is formed as an auxiliary adjustment in order to insure very close factory flow bench settings for individual carburetors. This comprises a high speed needle valve 3'7 controlling the admission of fuel to a passage 38 leading into the nozzle chamber 25. This needle valve allows a small amount of fuel to be fed past it into thenozzle system. The metering pin 22 is purposely made to give a slightly leaner l mixture than desired and the extra fuel required to give a proper mixture is fed past the high speed valve 37. In practice this valve is set at the factory and adjustment thereafter is unnecessary except for great changes in general operating conditions, as at high altitudes'.

I-n plain tube carburetors yit is necessary to supply fuel, for operation under idling conditions, above the throttle disc when closed, be cause under such conditions the air flow through the venturi is so slight that it will not pick u'p fuel from the main-nozzle. The idle fuel is taken out of the main nozzle through ak passage 39 leading from an annular chamber 40 formed in the shank of the main nozzle and communieating with the passage therethrough. vAn idle tube 41 has calibrated restrictions in both ends and the lower end is threaded into the passage 39. The upper end of the tube discharges into a passage 42 where it is mixed with air from a passage 43. The mixture of fuel and air then p'asses vinto a small chamber 44 and is discharged into the carburetor mixture outlet passage above, the edge of the closed throttle disc through an orice 45. A second passage 46 is positioned below the edge of the closed throttle disc and serves as an air bleed into the chamber 44 under such circumstances. When the throttle is increasingly opened from its extreme closed or idling position the lower pasd sage 46 is gradually exposed to the suction above the throttle and then delivers mixture from the chamber 44 to supplement the delivery from the upper passage or orice 45. In this .way an v versed to the extent of the lostl motion before increased flow of fuel passes through vthe idle system as the throttle is opened, until the main nozzle starts to deliver. The two idle discharge passages thus supplement each other and graduate smoothly into the normal nozzle discharge.

An idling adjustment is provided comprising a needle valve 48 controlling the admission of air from the passage 43 into the passage '42. By increasing the admission of air the suction on the idling tube is decreased thus thinning the idling mixture, and by decreasing the inflow of air this'suction will be increased thus increasing the delivery of fuel from the idling tube.

The main fuel nozzle 20 is of the air bleed type wherein air bleed holes 49 are formed in the nozzle at different elevations and are fed air from a well 50 surrounding the lower part of the idle tube. 'The top of the well 50 opens into an air inlet passage 51 extending down to the lower edge of the venturi and consequently drawing air from the main air inlet passage of the carburetor. The passage 51 also supplies the idle air passage 43.

When the carburetor is full of fuel the well 50 contains fuel and this condition holds true under idling conditions up until the main nozzle starts to deliver. WhenI the nozzle starts to dev' liver due to opening of the throttle the fuel in the well 50 flows through the uppermost air bleed holes 49. into the nozzle 20. As the air flow through -the venturi increases the remainder of the fuel in the nozzle chamber about the air bleed holes 49 flows through the lower air bleed hole into the nozzle. As soon as the fuel is out of the well 50 and the passage connecting the well to the nozzle chamber, air bleeds into the nozzle chamber 25 and thence through the air bleed holes 49 into the nozzle passage 35.

The throttle operated accelerating pump comprises a piston 52 operable in the cylinder 28, the piston having an upstanding stem 53 projectingthrough the cover 13 and having a lost motion connection 54 to the link 27, which incorporates the maximum-minimum metering pin operating Aarm 26, and which is pivoted to the end of a lever 56 secured to the throttle shaft. A frictionspring 57 acts against the stem 53 to take up the lost motion slack in such a way as to delay the movement of the accelerating pump in response to both opening and closing movements of the throttle. 'Ihe combination of the lost motion connection and friction spring holds the stem at any one position and allows the movement of the throttle to be rethe pump starts to operate. If, for example, a

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vehicle be allowed to coast, the we115o' nus with f 'Ihis is accomplished by providing a weighted 145 follower 58 surrounding the stem above the pis ton. A port 59 through the piston permits a portion of the fuel to enter between the follower and the piston during the downward movement of the piston and after the cessation of piston movement the weight of the follower forces the fuel back through the piston port 59 and out through the pump delivery passages leading to the main nozzle.

The air inlet passage 16 is provided with a choke valve disc 60 loosely mounted on a shaft 61 oset relative to a principal diameter of the passage to form an unbalanced valve. The choke valve disc is driven by the shaft through a lost motion connection afforded by the projection of a pin 62 through a limited slot 63 in that portion 'of the valve enveloping the shaft. Aspring 64 normally holds the valve advanced relative to the shaft so that the operation of the shaft through the usual dash control acting on a lever 65, fwill resiliently close -the valve by approximately a three quarters movement of the dash control, and the further final movement of the control will take up thev lost motion and thus hold the valve'rigidly closed. When the valve is only resiliently closed the unbalanced condition thereof causes it to automatically open in response to the suction of the engine, thus providing a yielding choke which facilitates starting under normal conditions, the rigid choke being required only for abnormally severe conditions. In the operation of this carburetor the idling fuel supply is metered in accordance with the throttle position which regulates the demand. The idling fuel thus increases in proportion to the throttle opening until the flow of air through the venturi is suicient to start delivery from the main nozzle, the transition point being well covered by the overlapping of delivery from the idling and main nozzle. When the main nozzle starts delivery the well 50 rst empties through the nozzle and is followed by the delayed and prolonged accelerating pump discharge thus giving a temporarily enrichened 4mixture to meet engine accelerating requirements. Under normal operation the well 50 will have been emptied and will then act as an air bleed into the main nozzle as previously described. If the demand on the engine increases short of wide open throt tle the increased suction on the nozzle will start additional ow. of fuel thereto through the accelerating pump passages, the increased suction being sucient to cause the flow of fuel past the non-return valves in these passages. The auxiliary lneedle valve serves to supplement the intentionally lean metering of the fuel supply as previously described, and thus compensates for manufacturing variations in individual carburetors.

The foregoing metering characteristics are so proportioned as to provide an economical mixture ratio up to practically full open throttle conditions. When maximum power is desired, a. richer mixture is needed and is obtained by the nal opening movement of the throttle acting to depress the maximum-minimum metering pin to increase the eiective area of the orice 23. The last stage of the throttle opening movement has relatively slight effect inincreasing the effective opening in the case of a butterfly throttle but by utilizing this movement to open the maximum metering pin a substantial increase in power output is obtained.

The resilient choke structure also serves to enrich the metering characteristics throughout the normal range, when such an adjustment is desirable due to operating conditions by increasing the carburetor suction under given conditions of load and speed and thus increasing the flow of fuel relative to the volume of enter-.-

ing air. The suction imposed on the choke valve tends to open the same thus limiting the increase in suction so obtainable unless the choke is rigidly closed.

It will (thus be seen thatI have invented an improved carburetor of the class described incorporating improved fuel metering characteristics for normal and maximum power together with accelerating means supplementing the normal metering means.

I am aware that many changes may be made and numerous details of construction may be varied through a wide range without departing from the principles of this invention, and I therefore do not purpose limiting the patent granted h'ereon otherwise than necessitated by the prior art.

I claim as my invention:

l. In a carburetor a nozzle, means for providing a metered fuel supply thereto, a fuel well which when emptied forms an air bleed into said nozzle, a throttle valve, an accelerating pump` discharging into said nozzle, a lost motion connection from said throttle to said accelerating pump for operating the pump after a pre- L00 determined movement of the throttle, and frictional retarding means associated with said pump for taking up the slack in said lost motion connection in each direction opposite to the movement of the throttle. l

2. In combination with a throttle controlled carburetor, an accelerating device comprising fuel pumping means including a chamber and a reciprocable piston therein, a lost motion connection between said throttle and said piston for controlling the mov/ementl of said piston, a weighted follower reciprocable in said chamber above said piston, and a means for introducing fuel between said piston and follower upon pumping action of said piston, whereby said `follower willv return said fuel and prolong the discharge of said accelerating device after the cessation of motion of said piston.

3. In combination with a throttle controlled carburetor, an accelerating device comprising fuel pumping means including a chamber and a reciprocable piston therein, a lost motion connection between said throttle and said piston for controlling the movement of said piston, and a frictional retarding device for holding back said piston to the 'limit of the slack in said lost motion connection in a direction opposite the last movement thereof.

ll. In combination with a throttle controlled plain tube carburetor including a fuel chamber and an air bleed type of fuel discharge nozzle in communication therewith, an accelerating device comprising fuel pumping means, a separate connection between the fuel chamber and the nozzle and subject to suction thereon for supplementing the normal fuel supply to said nozzle, a valve in said connection adapted to open under high suction conditions, and a connection between said throttle and saidpumping means including a lost motion link for retarding the responsiveness of said fuel pumping means.

5. In combination with' a throttle controlled plain tube carburetor including a fuel chamber and an air bleed type of fuel discharge nozzle in communication therewith, an accelerating device comprising fuel pumping means, a separate connection between the fuel chamber and the nozzle for supplementing the normal fuel supply to said nozzle under high suction conditions, and a connection between said throttle 150 and said pumping means including a lost motion link for retardng the responsiveness of said fuel pumping means, and friction means engaging said connection momentarily maintains the slack in the lost motion link upon reversal of the motion of said connection.

6. In combination with a throttle controlled plain tube carburetor including a fuel chamber and an air bleed type of fuel discharge nozzle in communication therewith, an accelerating device comprising fuel pumping means, ya separate connection between the fuel chamber and the nozzle for supplementing the normal fuel supply to said nozzle under high suction conditions, and a connection between said throttle and said pumping means including a lost motion link for retardng the responsiveness of said fuel pumping means, and means in said fuel pumping means for prolonging the discharge of fuel therefrom after cessation of motion of the connection between the throttle and the pumping means.

'7. In combination with a throttle controlled plain tube carburetor including a fuel chamber and an air bleed typev of fuel discharge nozzle in communication therewith, an accelerating device comprising fuel pumping means, a separate connection between the fuelcharnber and the nozzle for supplementing the normal fuel supply to'said nozzle under high suction conditions, and a connection between said throttle and said pumping means including a lost motion link for retardng the responsiveness of said fuel pumping means, and friction means engaging said connection momentarily maintains the slack in the lost motion link upon reversal of the motion of said connection, and means in said fuel pumping means for prolonging the discharge of fuel therefrom after cessation of motion of the connection betweenthe throttle and the pumping means.

8. In combination with a carburetor including a throttle, an accelerating device associated with said carburetor and including a cylinder, a piston in said cylinder having an operating connection' to said throttle, a weighted cylindrical element independently movable in/ said cylinder above said piston, a fluid port through said piston whereby the pumping operation of said piston discharges a portion ofthe fuel above the pistonra'nd beneath the weighted element, said weighted element thereby serving to return the fuel so discharged after the cessation of the pumping motion of said piston to prolong the discharge period of said accelerating device. e

9 In combination with a carburetor including a throttle, an accelerating device associated with said carburetor andr including a cylinder, a

piston in said cylinder having an operating connection to said throttle, said operating connection having a lost motion link therein to reduce the responsiveness of the accelerating device at small throttle movements, and retardng means for said operating connection to hold back the operation of said device to the limit of the slack therein. l

10. In a plain tube carburetor including a throttle, an air bleed fuel nozzle, means supplying fuel directly thereto, a fuel pump discharging into said nozzle, fuel supply passages to and from said pump so arranged as to form a secondary source of fuel supply to said nozzle athigh suctions when the pump is inoperative, a suction responsive valve normally closing said passages and means for operating said pump from said throttle, including means for retarding Athe initial responsiveness of said pump to throttle movements in either direction.

11. In a plain tube carburetor` including a throttle, an air bleed fuel nozzle, means supplying fuel directly thereto, a fuel pump discharging into said nozzle, fuel supply passages to and from said pump so arranged as to form a secondary source of fuel. supply to said nozzle at i high suctions when the pump is inoperative and means for operating said pump from said throttle, and means associated with said pump for retardng the delivery of a portion of the fuel displaced by said pump until after the cessationA of the pump stroke, whereby to prolong the fuel discharge for an interval after the pump has ceased its motion.

12. In a plain tube carburetor including a throttle, an air bleed fuel nozzle, means supplying fuel directly thereto, a fuel pump discharging into said nozzle, fuel supply passages to and from saidV pump so arranged as to form a secondary source of fuel supply to said nozzle at high suctions when the pump is inoperative and means for operating said pump from said throttle, including means for retardng the responsiveness of said pump to throttle movements, and means associated with said pump for retardng the deliveryof a portion of the fuel displaced by said pump until after the cessation of the pump stroke, whereby to prolong the fuel discharge for an interval after the pump has ceasedL its motion.

13. In a carburetor including a throttle, an accelerating device associated With the carburetor and including a cylinder, a piston in said cylinder having a sliding fit therewith, a stem projecting upwardly from said piston and having an operating connection with the throttle, a Weighted annular element independently movable in, said cylinder above said piston and having a sliding fit with said stem and said cylinder, and a fluid port through said piston whereby the downward stroke of said piston forces a' portion of the fuel above the piston and beneath 'the weighted element, said weighted element falling by gravity after completion of the downward stroke of the piston to force out the fuel from between the element and the piston to prolong the discharge period of said accelerating device.

`14. In a carburetor, a throttle, a fuel nozzle discharging into the carburetor, means supplying fuel directly to the nozzle and a device for supplying additional` fuel to said nozzle for accelerating purposes comprising a cylinder, a piston in said cylinder having a sliding t therewith to form a first fuel discharging means, a positive mechanicalI connection between said throttle and said piston to effect a downward discharge movement thereof upon opening movement of said throttle, a second discharge means comprising a second piston coaxial with said first piston, and an annular surface on said first piston engaging said second piston to support the same in inoperative position, said second piston falling by gravity after release by downward discharging movement of said rst piston to discharge additional fuel to the nozzle' and thereby extend the period of accelerating supply after the first piston has ceased its movement.

15. In a plain tube carburetor, a throttle, an air bleed fuel nozzle, means supplying fuel directly thereto, and a device for supplying additional -fuel to said nozzle for accelerating purposes comprising a first cylinder and piston position, said second means operating by gravity after release by discharge movement of said rst means to discharge fuel and thereby extend v the period of discharge after the first means has ceased its movement.

HOWARD W. V LINKERT. 

